Printer and extractable module therefor

ABSTRACT

A printer and a module for supporting a paper roll therefore, the module comprising: a body for housing the roll; a first supporting member for the roll before that the roll is unwound for the printing operation; a second supporting member for the roll, after the roll has been wound at the end of printing operations; and a first engaging member carried by said body and disposable in a first configuration wherein it is coupled with a second engaging member carried by the printer to secure the module on the printer; the first engaging member is further disposable in a second configuration, wherein it is released from the second engaging member to permit the extraction of the module from the printer.

The present invention relates to a printer and to an extractable modulefor such a printer.

Businesses are known to employ printers, which print sales receiptsintended for customers, and a copy of the same receipts which, for taxreasons, must be stored in a remote location from the printer accordingto a given procedure.

More specifically, known printers substantially comprise a print head; afirst roll (receipt paper roll) housed inside a seat on the printer andon which the print head prints the sales receipts; and a second roll(journal paper roll), also housed inside the seat and on which the printhead prints the copy of the sales receipts, hereinafter referred to forthe sake of simplicity as the tax copy.

The first roll (typically wound onto an inner support) is mounted on afirst shaft located inside the printer seat. During printing operations,the first roll is unwound off the first shaft so that a free end of theroll is positioned along the traverse path of the print head; the printhead can therefore print the sales receipt on that free end, which isthen torn off the first roll and given to the customer.

Similarly, the second roll (typically wound onto an inner support) ismounted on a second shaft located inside the printer seat. Duringprinting operations, the second roll is unwound off the second shaft,and is rewound onto a third shaft also housed inside the seat. For thispurpose, the second roll is fitted idly to the second shaft, and has oneend fitted securely inside a slot on the third shaft. During the aboveoperation, the second roll has an unwound intermediate portion,interposed between the second and third shaft, positioned along thetraverse path of the print head alongside the free end of the firstroll; the print head can therefore print the copy of the sales receipts(tax copy) on that intermediate portion.

The printer head prints on the free end of the first roll and on theintermediate portion of the second roll during the same stroke; inparticular, it prints firstly on the first roll paper and then on thesecond roll paper.

After each traverse of the printing head, the third shaft is rotated tounwind the second roll off the second shaft and wind the second rollonto the third shaft.

When wound completely onto the third shaft, the second roll must beremoved from the seat to be stored in a suitable remote location fromthe printer.

More specifically, the second roll and the third shaft are removedjointly from the seat on the printer, and the second roll is thenremoved from the third shaft for suitable storage.

Also the second shaft is removed from the seat on the printer, to allowidle fitting thereon of a blank second roll and insertion thereof insidethe seat on the printer.

The third shaft is in turn inserted inside the seat on the printer.

At this point, one end of the second roll is drawn off the second shaftand threaded inside the slot on the third shaft to secure the secondroll to the third shaft.

The above-described operations of removing and inserting the second rollcan cause prolonged hold-ups and hence inconvenience to customers.Demand therefore exists in this particular sector to reduce customerwaiting time.

The above operations are also extremely awkward, in that, to reduceoverall size, known printers allow very little space between the edge ofthe seat and the fully-wound second roll on the third shaft.

JP2000048258 A in the name of Fujitzu General LTD relates to a cashregister and deals with the problem of replenishment with a journal anda receipt. To exchange the roll paper, a cover is rotated by a rotationmechanism, opened backward, the printed journal is rotated by a rotaryshaft and raised upward, a journal roll paper is put on a roll paperholder, its tip is put through a printer and fixed to a journal windingpart, a receipt roll paper is put on a roll paper holder and its tip isput through a printer. The journal holder is returned to its originalposition and the cover is closed.

In the cash register model Euro-2100 of Elcom, paper roll change must becarried out according to the following steps. A control button must bepressed to flip a tape cover open. A paper tape separator is taken outalong with empty paper reel cores, which are then removed; new papertape reels can now be installed. The separator can be inserted withinstalled tapes into a rear cover. The journal tape is then insertedinto the printer, and the printer will load the tape automatically intoits mechanism. Then the end of journal tape must be placed into awinding reel, which must be rotated in the winding direction severaltimes. The winding reel must then be placed into the rear cover in suchway that it will be highly stretched.

Demand therefore also exists to make removal and insertion of the secondroll easier, while limiting the overall size of the printers.

It is an object of the present invention to propose a technique to makeeasier and faster the replacement of a paper roll from a printer, inparticular the replacement of a paper roll adapted to provide tax copiesof sales receipts from a printer for point of sales.

The proposed solution lies in the use of a preassembled module housingthe paper roll, adapted to be easily inserted in and extracted from aprinter seat, and adapted to be easily disassembled for removing thepaper roll. Accordingly, the module containing the finished roll can bequickly extracted from the printer, and with the same quickness bereplaced with an already prepared module housing a new roll.

The disassembly of the module can be performed in a second time, withoutresulting in a detrimental waiting time.

According to a first aspect thereof, the present invention thereforerefers to a printer comprising a main body and a module associated withthe main body for supporting a printable member; the module comprising:

a housing body;

a first supporting member associated to the housing body and adapted tosupport a roll of the printable member before it is unwound forexecuting a print operation on the printable member, and a secondsupporting member associated to the housing body and adapted to supportsaid roll once the roll has been wound upon completion of a printoperation; and

at least a first fastening member carried by the housing body and atleast a second fastening member carried by the main body; the first andthe second fastening member being settable in a first reciprocalposition, in which they are coupled to secure the module to the mainbody, and in a second reciprocal position, in which they are released topermit removal of the module from the main body.

Preferably, the first supporting member is adapted to support idly theroll and the second supporting member is connected releasably to thehousing body for being extracted therefrom together with the roll.

The housing body may be open at least at one side to allow theextraction of the roll and the second supporting member from the module.

The housing body may be frame-shaped and may comprise two wallsconnected releasably to opposite ends of the second supporting member.

Such walls may be adapted to flex apart to permit removal of the rolland the second supporting member.

The first and the second fastening member may be click-on fasteningmembers.

The printer may also comprise an elastic coupling member acting on oneof the first and second fastening members for disposing the firstfastening member into the first reciprocal position.

The first fastening member may comprise at least one tooth and thesecond fastening member may comprise at least one projection connectableto the tooth.

The first fastening member may comprise two such teeth angularlyintegral with each other and the second fastening member may comprisetwo such projections, each connectable releasably to a respective tooth.

The module may also comprises a pin suitable to rotate with respect tothe housing body and angularly integral with the teeth, and an elasticcoupling member interposed between the pin and said housing body.

The printer may also comprise a release lever angularly integral withthe tooth, and which is operated to move the first fastening member fromthe first reciprocal position to the second reciprocal position inopposition to the elastic coupling member.

The module may comprise at least a first positioning member connectableto at least a second positioning member carried by the main body, to setthe first and second fastening member to a predetermined relativeposition inside the seat, in which they click onto each other.

The at least a first positioning member and the at least a secondpositioning member may have conjugate profiles.

The printer may also comprise a wheel angularly integral with one of thefirst and second supporting members and functionally connectable to adrive member to unwind the roll off the first supporting member and windthe roll onto the second supporting member.

The housing body may carry at least a roller provided to press a portionof the roll against a guiding member during printing of the portion.

The housing body and the roller are elastically connected to each other.

The present invention further relates to a module for supporting aprintable member and adapted to be housed in a printer for permittingprinting operation on the printable member; characterized in comprising:

a housing body;

a first supporting member associated to the housing body and adapted tosupport a roll of the printable member before it is unwound to executethe printing operations, and a second supporting member associated tothe body and adapted to support the roll once it has been wound at theend of printing operations; and

at least a first fastening member carried by the body and adapted tocouple releasably with a second fastening member carried by the printerto permit a fixed mounting of the module into the printer and extractionof the module from the printer.

A preferred, non-limiting embodiment of the present invention will bedescribed by way of example with reference to the accompanying drawings,in which:

FIG. 1 shows a view in perspective of a preassembled module inaccordance with the present invention, and of a printer in which toinsert the preassembled module;

FIG. 2 shows an exploded view in perspective of the preassembled modulein FIG. 1;

FIGS. 3 and 4 show two larger-scale views in perspective, from differentangles and with parts removed for clarity, of the preassembled moduleand printer in FIG. 1;

FIG. 5 shows a much larger-scale view in perspective of a detail ofFIGS. 3 and 4;

FIG. 6 shows a view in perspective of further details of FIG. 1;

FIG. 7 shows a view in perspective of the preassembled module and theprinter of FIG. 1 during an extraction step.

Number 2 in FIG. 1 indicates a printer 2 suitable to print on a firstroll 4 (of printable material, preferably paper) sales receiptsindicating the amount received for given articles and intended for thepurchasers of said articles, and also to print on a second roll 16 (ofprintable material, preferably paper) a copy of such sales receipt (taxcopy), which for tax reasons must be stored in a remote location fromprinter 2.

More specifically, printer 2 comprises a frame 3, defining a main bodyof the printer and made of a plurality of parts, and a print head (notshown in the attached figures) mounted on a carrier 5, which movesinside the frame 3.

Frame 3 comprises a front and a rear portion 6, 7 and two side panels 8,9, and is designed to house the first roll 4 and the second roll 16. Thefirst roll 4 is housed in a first seat 13 of the frame 3 and it issupported so that it can rotate about an axis A. More in detail, roll 4is mounted for rotation on a shaft 11 driven by a motor (not shown) tounwind roll 4 off shaft 11.

The carrier 5 provided with the print head is movable along a directionparallel and offset with respect to axis A to print the paper of roll 4,so generating the sales receipts.

In particular, frame 3 defines inwardly a path (not shown) for the paperunwound from the roll 4 such that an end portion 12 thereof can bepositioned along the traverse path of the printer head, to permitprinting of the sales receipt thereon.

The printer 2 comprises an extractable module 1 suitable to house thesecond roll 16. Frame 3 comprises a second seat 10 lateral to the firstseat 13 and provided for housing module 1.

Module 1 (FIGS. 1 to 4 and FIG. 6) comprises a body 50 housing andsupporting the roll 16. As shown in detail in FIG. 2, body 50 comprisesa frame 15, a re-winding spool 52 and a member 20 adapted to connectmodule 1 and printer 2 one another.

Member 20 defines a first fastening element, which can be set to a firstconfiguration (coupling configuration) wherein it is engaged with asecond fastening element 21 (FIGS. 1, 3, 4) on printer 2 to securemodule 1 onto the printer 2, and to a second configuration (releaseconfiguration) wherein it is disengaged from the second fasteningelement 21 to permit removal of module 1 from printer 2.

Therefore, when the module 1 is housed into the seat 10, the cooperationbetween the first fastening element 20 and the second fastening element21 secures it inside the seat 10.

The frame 15 supports a shaft 17 (visible only in FIG. 2) extendingalong an axis C, for supporting the second paper roll 16 to be subjectedto print operations. Furthermore, frame 15 is adapted to support thespool 52 in a rotary manner about an axis D extending parallel to theaxis C, so that spool 52 can receive the paper subjected to print andrewind the paper roll 16. Therefore, roll 16 is designed to be supportedby shaft 17 and to be progressively unwound from shaft 17 and wound onshaft 18.

When module 1 is inserted inside seat 10, axes C and D are parallel toaxis A.

With reference to FIG. 2, spool 52 comprises a shaft 18 to be locatedalong axis D and a couple of circularly-shaped flanges 32, 33, which arecoupled to the shaft 18 at opposite ends thereof. Preferably, flange 32is integral with the shaft 18 whilst the flange 33 is releasable fromshaft 18.

Frame 15 comprises, on opposite sides, a wall 27 perpendicular to axes Cand D, and an arc-shaped wall 28 parallel to wall 27.

Frame 15 also comprises a wall 26 defining a sliding surface for aportion of roll 16 during unwinding off shaft 17 and winding onto shaft18.

More precisely, wall 26 extends between walls 27, 28, and isperpendicular to walls 27, 28 and parallel to axes C, D.

Wall 26 is on the front portion of the module 1 when the module 1 ismounted on the printer 2, and the surface of wall 26 on which theportion of roll 16 unwound off shaft 17 and to be wound onto shaft 18slides is a front surface of wall 26. Shafts 17 and 18 are on theopposite side of wall 26 with respect to the above-mentioned surface ofwall 26.

Frame 15 finally comprises a wall 29 extending between walls 27 and 28,on the opposite side to wall 26, i.e. on the rear portion of the module1 when the module 1 is mounted on the printer 2.

Frame 15 defines a space extending between the walls 27, 28 and providedto house the spool 52 and the roll 16 (initially held by shaft 17); thisspace is open at its opposite ends adjacent to shafts 17 and 18, tomaximise the size of the roll 16 that can be unwound off shaft 17 andwound onto shaft 18, and to permit removal of roll 16 from frame 15 onceit is wound fully onto shaft 18.

Shaft 17 (FIG. 2) projects from wall 27, is hollow, and houses a spring(not shown) for keeping shaft 17 pressed against roll 16 and preventingaccidental, spontaneous unwinding of roll 16.

In use, roll 16 is fitted idly onto shaft 17 and the free end of roll 16is coupled with shaft 18 so that the rotation of shaft 18 about axis Dwinds roll 16 onto shaft 18. More particularly, shaft 18 has one or moreslots 34, two in the shown embodiment, engageable by the end of roll 16.Once wound fully onto shaft 18, the roll 16 is detached completely fromshaft 17.

Each of the opposite axial ends of shaft 18 (only one shown in FIG. 2)comprises a coupling member in the form of a lance 30 extending alongaxis D. Lances 30 project through flanges 32, 33 and are designed to behoused releasably inside respective seats 53 a, 53 b formed in walls 27,28.

Walls 27, 28 have a certain flexibility and can be flexed apart torelease lances 30 from the respective seats 53 a, 53 b.

Flange 32 is fitted laterally, on the opposite side to flange 33, with agear 35 (shown in FIGS. 1, 3, 4, 5 and 7) which rotates about axis D andmeshes with a gear 36 (shown in FIGS. 3, 4, 6 and 7) fitted to printer2.

More specifically, gear 36 is housed (when the module 1 is housed insidethe printer 2) inside seat 10 and rotated, parallel to axes C and D andsynchronously with rotation of shaft 11 about axis A, by a mechanism notshown.

Spool 52 can therefore be rotated with respect to axis D to unwind roll16 off shaft 17 and synchronously wind roll 16 onto shaft 18.

Once module 1 is fixed inside seat 10 by the first and second fasteningelement 20, 21, the portion of roll 16 sliding along wall 26 is locatedalongside portion 12 of roll 4, along the traverse path of the printhead.

The first fastening element 20 comprise two teeth 40 (FIGS. 1 to 4 andFIG. 6), and the second fastening element 21 comprise two projections 42(FIGS. 1, 3, 4) projecting inside seat 10 and each of which clicks ontoa respective tooth 40. In particular, as shown in FIG. 1, one projection42 protrudes from a wall 41 delimiting laterally the seat 10 and theother projection (not visible) protrudes from an opposite wall.

With particular reference to FIGS. 2 and 6, teeth 40 extend fromopposite axial ends of a pin 43 housed behind wall 26 and rotating aboutan axis E parallel to axes C, D. More specifically, teeth 40 projectfrom pin 43 towards shaft 17.

Teeth 40 are loaded by a spring 44 (FIG. 2) into an angular position inwhich they click onto projections 42 to retain module 1 inside seat 10on printer 2. Spring 44 is a coil spring wound onto pin 43 and fixed atopposite ends to wall 26 and pin 43.

First fastening element 20 also comprises an operating lever 45extending integrally from one of teeth 40. When operated manually, lever45 rotates teeth 40 and pin 43 integrally, in opposition to spring 44,to release teeth 40 from projections 42 and so release module 1 fromseat 10 on printer 2.

It is clear that the coupling/release mechanism could comprise anoperating member (equivalent to the lever 45) and an elastic member(equivalent to the spring 44) both carried by frame 3 of printer 2.

Frame 15 also comprises a positioning member 47 (FIGS. 1 to 4), which isfitted integrally to wall 27, is elongated in shape in a directionperpendicular to axis D and parallel to wall 27 (in a downward directionwhen module 1 is fitted in seat 10).

Member 47 is fittable inside a further positioning member 48 on the sidepanel 8 of printer 2 (FIGS. 3 and 4), having a conjugate profile withrespect to member 47, in particular defining a groove wherein the member47 can slide. The profiles are designed so that the member 47 can slidedown to an end position in which teeth 40 click onto projections 42.

Members 47 and 48 thus simplify insertion of module 1 inside seat 10into the position in which teeth 40 click onto projections 42.

Module 1 further comprises a number of a paper contrast roller 55 (shownonly in FIG. 2), in the shown embodiment in number of two.

Each roller 55 is mounted on a relative pad 56 in a rotary way about anaxis parallel to axes C, D, E.

Pads 56 and frame 15 are connected each other by helically-shapedsprings 57, which load pads 56 and rollers 55 against the portion ofroll 16 unwounding from shaft 17 and to be subjected to print.

In particular, rollers 55 press said portion of the roll 16 againstguiding rollers (not shown) of the printer, so maintaining such portionin the required position and allowing a correct execution of theprinting operations.

In particular, the pressure exerted by rollers 55 avoids that, duringthe printing of two consecutive lines on the portion of the roll 16,said portion bends and loses its alignment with the printer head.

Operation of module 1 will be described as of the operatingconfiguration in which module 1 is inserted inside seat 10 on printer 2.

More specifically, module 1 is housed inside seat 10 so that the portionof roll 16 sliding along wall 26 is located alongside portion 12 of roll4 and facing the print head.

In this configuration, teeth 40 are clicked onto projections 42 toretain module 1 inside seat 10.

Carrier 5 with printer head moves parallel to axis A so allowing firstthe roll 4 end portion 12, then the sliding portion of roll 16, to beprinted, so as to obtain the sales receipt and copy thereof.

Once printed, the sales receipt is torn off and handed to the customer,and shaft 11 is rotated by the relative motor (not shown) to position ablank end portion 12 facing print head.

At the same time, gears 36, 35 are rotated to rotate spool 52 about axisD. The rotation direction of spool 52 is such as to unwind roll 16 offshaft 17 and wind roll 16 onto shaft 18. A blank portion of roll 16 thusslides along wall 26 into a position facing the print head. By the timeroll 16 terminates its function (i.e., it has been completely printed),it is wound completely onto shaft 18.

To preserve the tax copy, module 1 must be removed (FIG. 7) from seat10, and then, when module 1 is located outside of the printer 2, theroll 16 can be removed from body 15.

More specifically, using lever 45, pin 43 and teeth 40 are rotated inopposition to spring 44. In particular, teeth 40 are rotated into anangular position releasing projections 42 and permitting removal ofmodule 1 from seat 10.

A second module 1, assembled beforehand and containing a blank roll 16held by its shaft 17, is fixed inside seat 10 on printer 2. Moreprecisely, the second module 1 is inserted by feeding member 47 intogroove defined by member 48 into a position in which teeth 40 click ontoprojections 42.

At this point, print head can resume operation, printing the salesreceipts on roll 4 and the tax copy on roll 16.

Roll 16, on which the tax copy is printed, can be easily removed fromthe extracted module 1; typically the finished roll 16, held by spool52, is removed from the extracted module 1 after that new module 1 hasbeen inserted into printer 2 and in a remote location from printer 2. Toremove roll 16, walls 27, 28 are flexed apart so as to release lances 30from the respective seats 53 a, 53 b in walls 27, 28.

Spool 52 and roll 16 are then removed integrally from body 15 in anextraction direction F (FIG. 1) perpendicular to axis C and parallel towalls 27, 28.

At this point, flange 33 is removed from shaft 18 and roll 16 isdetached from shaft 18 and stored in the tax copy store.

Finally, the module 1 can be re-assembled with a blank roll 16 and madeavailable at printer 2.

First of all, the spool 52 is re-assembled (by coupling flange 33 andshaft 18 each other) and coupled again with frame 15 (by housing lances30 inside the respective seats 53 a, 53 b of the walls 27, 28).

The blank roll 16 is fitted idly onto shaft 17, and an end portion ofroll 16 is run along wall 26 and securely fitted inside the slot 34 onshaft 18. Shaft 18 is then rotated a few turns about axis D to securethe paper of roll 16 firmly to shaft 18.

The module 1 so formed can is ready to be inserted, when required,inside seat 10 on printer 2.

The advantages of printer 2 according to the present invention will beclear from the foregoing description.

In particular, with respect to the known solutions described in theintroductory portion of the present description, the use of module 1allows to reduce the number of operations which are necessary to changeroll 16, so minimizing the length of time customers are kept waiting.

In fact, customers have to wait only for the time necessary to removemodule 1 from seat 10 and to insert into seat 10 the second module 1provided with a blank roll 16, whilst the operation of removing fromremoved module 1 the roll 16 on which the tax copy is printed may beperformed when the second module 1 is already inserted into printer 2,for instance in a moment in which there is no customers waiting.

Moreover, the operation of removing roll 16 with the tax copy andinserting the blank roll 16 are simplified greatly by being performedoutside seat 10 of printer 2.

Finally, the overall size of printer 2 is reduced as provision of spacesfor inserting fingers of the operator between seat 10 and roll 16 toperform the above-mentioned operations is not necessary.

Clearly, changes may be made to preassembled module 1 and printer 2 asdescribed and illustrated herein without, however, departing from thescope defined in the accompanying claims.

1-17. (canceled)
 18. A printer, comprising a main body and a moduleassociated with the main body for supporting a printable member, saidmodule comprising: a printable member housing body; a first supportingmember associated to said housing body and adapted to support a roll ofsaid printable member before it is unwound for the execution of a printoperation on said printable member, and a second supporting memberassociated to said housing body and adapted to support said roll oncethe roll has been wound upon completion of the print operation; and atleast a first fastening member carried by said housing body and at leasta second fastening member carried by said main body; said first andsecond fastening member being settable in a first reciprocal position,in which they are coupled to each other to secure said module to saidmain body, and in a second reciprocal position, in which they arereleased from each other to permit removal of said module from said mainbody.
 19. A printer as claimed in claim 1, characterized in that saidfirst supporting member is adapted to support idly said roll; and inthat said second supporting member is connected releasably to saidhousing body for being extracted therefrom together with said roll. 20.A printer as claimed in claim 2, characterized in that said housing bodyis open at least at one side to allow the extraction of said roll andsaid second supporting member from said module.
 21. A printer as claimedin claim 3, characterized in that said housing body is frame-shaped andcomprises two walls connected releasably to opposite ends of said secondsupporting member.
 22. A printer as claimed in claim 4, characterized inthat said walls are adapted to flex apart to permit removal of said rolland said second supporting member.
 23. A printer as claimed in claim 1,characterized in that said first and second fastening member areclick-on fastening members.
 24. A printer as claimed in claim 1, furthercomprising an elastic coupling member acting on one of said first andsecond fastening member for disposing said first fastening member intosaid first reciprocal position.
 25. A printer as claimed in claim 1,characterized in that said first fastening member comprises at least onetooth; and in that said second fastening member comprises at least oneprojection connectable to said tooth.
 26. A printer as claimed in claim8, characterized in that said first fastening member comprises two teethangularly integral with each other; and in that said second fasteningmember comprises two projections, each connectable releasably to arespective tooth.
 27. A printer as claimed in claim 9, characterized inthat said module comprises a pin which can rotate with respect to saidhousing body and is angularly integral with said teeth, and an elasticcoupling member interposed between said pin and said housing body.
 28. Aprinter as claimed in claim 10, further comprising a release leverangularly integral with said tooth, and which is operated to move saidfirst fastening member from said first reciprocal position to saidsecond reciprocal position in opposition to said elastic couplingmember.
 29. A printer as claimed in claim 1, characterized in that saidmodule comprises at least a first positioning member connectable to atleast a second positioning member carried by the main body, to set saidfirst and second fastening member to a predetermined relative positioninside the seat, in which they click onto each other.
 30. A printer asclaimed in claim 12, characterized in that said at least a firstpositioning member and said at least a second positioning member haveconjugate profiles.
 31. A printer as claimed in claim 1, furthercomprising a wheel angularly integral with one of said first and secondsupporting member and functionally connectable to a drive member tounwind said roll off said first supporting member and wind said rollonto said second supporting member.
 32. A printer as claimed in claim 1,characterized in that said housing body carries at least a rollerprovided to press a portion of said roll against a guiding member duringprinting of said portion.
 33. A printer as claimed in claim 15,characterized in that said housing body (and said roller are elasticallyconnected to each other.
 34. A module for supporting a printable memberand adapted to be housed in a printer for permitting a printingoperation on said printable member, characterized in that it comprises:a printable member housing body; a first supporting member associated tosaid housing body and adapted to support a roll of said printable memberbefore it is unwound to the execution of the printing operation, and asecond supporting member associated to said housing body and adapted tosupport said roll once it has been wound upon completion of the printingoperation; and at least a first fastening member carried by said housingbody and adapted to couple releasably with a second fastening membercarried by said printer to permit a fixed mounting of said module intosaid printer and extraction of said module from said printer.